There can be no guarantees re effectiveness because every person's hair and skin colour and hormonal make-up is different. Also, 'permanent,' with regard to hair removal, is a legal word and it's definition varies from country to country.
Permanent reduction is a huge benefit though which is why, if virgin waxing was not effective, I'd offer her laser treatment. I'd like to see clinical evidence about virgin waxing, because if it is effective, it is significantly less expensive than laser and MUCH less painful than electrolysis, which is incredibly painful and incredibly time-consuming and expensive, and can cause scarring.
Bikini waxing is not extremely painful anyway. Much less than lower leg waxing, especially tops of legs with little fat/muscle covering. I would also have her legs and underarms waxed, with her permission of course.
Anyway all of this would just hurt for a second. Not as painful as repeated waxing in adulthood, not as time-consuming as shaving, not as painful as teasing, lack of confidence, etc.
It's pretty likely I'd have a daughter with hirsutism, as it runs in my family. I'm not talking about taking a child with normal body hair.
Anyway, taking a 9 year old for waxing is not about making 9 year olds hairless, it's about making the adults they will become hairless. Big difference. If you have to get the hairs before puberty, you have to get them around that age. If it works. We don't know, I don't think.
And...yes, a hirsute child WILL care about those nasty girls. And boys. And adults. And society. Fact. No matter how 'supportive' and 'positive' her mother is about her hairiness, telling her it doesn't 'matter' (which is what my mother did, and it trivialized my feelings).
Re the cultural stuff, I was saying that to counter the argument that hair removal practices are patriarchal and stem from infantalizing porn. And...not.
Ancient Egypt, Greece, Rome...in fact prehistoric humans, male and female, have been removing hair from bodies including genitals for thousands of years.
Only in the West has hair removal for women been slow to catch up.
I find all this judgement quite shocking. Who needs patriarchy when you have other women?
Oh, and I like pierced ears on little girls too. Might as well show my true colours.